September- Putaputawētā - Native Plant of the Month

Putaputawētā

Carpodetus serratus

Putaputawētā leaves showing characteristic marbling.

Putaputawētā are elegant, endemic, small trees that grow throughout the bush understory across Aotearoa. They particularly like growing on bush margins and stream banks, which make them quite easy to spot. Putaputawētā will happily grow in a shaded spot in your garden as long as you have reasonably rich soil. They will even thrive in damp spots that might be standing water for several months of the year, making them ideal for swampy locations. You can often see putaputawētā happily keeping kahikatea and cabbage trees company in wetland restoration sites.






Juvenile putaputawētā (Photo Laura Dillon iNaturalist CC BY-NC)

Putaputawētā, like many of our native trees, have different juvenile and adult forms. Saplings have small leaves that are arranged alternately along zig-zagging fine branches. These young branches are arranged in horizontal tiers that give young trees a fine symmetry. As the trees mature their leaves will double in size and their branches become more dense and straight. Often you can find shoots of juvenile foliage on mature trees, which means you can compare the two growth forms on the same plant. Putaputawētā flower in late spring/early summer with clusters of small, white, star-shaped blooms. These form rounded, hard fruits with a distinct circling rim around their tops. The fruit begin a dark green colour and ripen to a purple-black in late summer/autumn. They are eaten by birds, which disperse the seeds.

Putaputawētā in flower (Photo by JM Homewood iNaturalist CC BY-NC)

Putaputawētā are trees that go by many names and each are wonderfully descriptive. The first, marbleleaf, is an ode to the mottled colouration of the leaves. These are much darker around the leaf veins, producing a marbled effect that is most clearly seen from below. Another, less common, name is bucket-of-water tree. Putaputawētā don’t pour water from their cut timber, but their wood is notoriously sappy, reluctant to burn and doesn’t give off much heat when it does. Adding putaputawētā wood to a fire is apparently akin to throwing a bucket of water on it! Finally, the name putaputawētā, as you might have guessed, refers to wētā… many many wētā. The very-many-wētā described in this name live in the numerous holes that putaputawētā trunks usually bear. They hide in these holes during the day snug and safe from any hungry mice, rats or birds and then emerge at dusk to feed.

Putaputawētā trunk with holes and scars from pūriri moth caterpillars (photo by Tony Wills iNaturalist CC BY-SA)

While putaputawētā are clearly an important habitat for wētā, the holes that they live in are not made by them. Instead they are made by another of our remarkable and endemic insects - the caterpillars of the pūriri moth. Pūriri moth caterpillars bore large holes into the trunks of many of our native (and exotic) trees. They create a springy web of silk over their holes to disguise it from curious predators (and fingers!) and emerge at night to feed on the tree’s bark around the edge of their hole under the protective silk layer. These caterpillars can live in their snug tree holes anywhere between 8 months and 7 years! Pūriri moths may be named after the pūriri trees that also sport caterpillar holes, but putaputawētā are one of these caterpillars’ top tree choices. This makes them a very important part of the pūriri moth life cycle, particularly in parts of the country where pūriri don’t grow. Even very small putaputawētā trees usually have holes or scars from these caterpillars. Pūriri moths are our largest native moth species and are found nowhere else in the world. While pūriri moths and wētā are some of our largest native insects, putaputawētā also support a range of smaller native insects. Small brown bush ants (Prolasius advenus) feed on the trees’ sap that wells from the wounds the pūriri moth caterpillars create. Putaputawētā flowers also attract plenty of native pollinating insects, including our small native bees.

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